企業(yè)級應(yīng)用系統(tǒng)體系架構(gòu)SOA概述課件

企業(yè)級應(yīng)用系統(tǒng)體系架構(gòu)（八）

SOA概述ChenHaopengTuesday,November22,2022References：IBMRedbook:PatternsServiceOrientedArchitectureandWebServices1企業(yè)級應(yīng)用系統(tǒng)體系架構(gòu)（八）

SOAThebusinessdriversforanewapproachWhileITexecutiveshavebeenfacingthechallengeofcuttingcostsmaximizingtheutilizationofexistingtechnologyAtthesametimetheyhavetocontinuouslystrivetoservecustomersbetterbemorecompetitivebemoreresponsivetothebusiness’sstrategicpriorities.Therearetwounderlyingthemesbehindallofthesepressures:HeterogeneityandchangeThebusinessdriversforanewThebusinessdriversforanewapproachHeterogeneity

Mostenterprisestodaycontainarangeofdifferentsystems,applications,andarchitecturesofdifferentagesandtechnologies.Integratingproductsfrommultiplevendorsandacrossdifferentplatformswerealmostalwaysanightmare.Butwealsocannotaffordtotakeasingle-vendorapproachtoIT,becauseapplicationsuitesandthesupportinginfrastructurearesoinflexible.ChangeGlobalizationande-businessareacceleratingthepaceofchange.Improvementsintechnologycontinuetoaccelerate,feedingtheincreasedpaceofchangingcustomerrequirements.ThebusinessdriversforanewThebusinessdriversforanewapproachAsaresult,businessorganizationsareevolvingfromthevertical,isolatedbusinessdivisionsofthe1980’sandearliertothehorizontalbusiness-process-focusedstructuresofthe1980’sand1990’stowardsthenewecosystembusinessparadigm.Businessservicesnowneedtobecomponentizedanddistributed.Thereisafocusontheextendedsupplychain,enablingcustomerandpartneraccesstobusinessservices.ThebusinessdriversforanewThebusinessdriversforanewapproachQuestions:HowdoImakemyITenvironmentmoreflexibleandresponsivetotheeverchangingbusinessrequirements?Howcanwemakethoseheterogeneoussystemsandapplicationscommunicateasseamlesslyaspossible?Howcanweachievethebusinessobjectivewithoutbankruptingtheenterprise?CurrentlymanyITexecutivesandprofessionalsalikebelievethatnowwearegettingreallyclosetoprovidingasatisfactoryanswerwithservice-orientedarchitecture.ThebusinessdriversforanewThebusinessdriversforanewapproachInordertoalleviatetheproblemsofheterogeneity,interoperabilityandeverchangingrequirements,suchanarchitectureshouldprovideaplatformforbuildingapplicationserviceswiththefollowingcharacteristics:LooselycoupledLocationtransparentProtocolindependentBasedonsuchaservice-orientedarchitecture,aserviceconsumerdoesnotevenhavetocareaboutaparticularserviceitiscommunicatingwithbecausetheunderlyinginfrastructure,orservice“bus”,willmakeanappropriatechoiceonbehalfoftheconsumer.Theinfrastructurehidesasmanytechnicalitiesaspossiblefromarequestor.ParticularlytechnicalspecificitiesfromdifferentimplementationtechnologiessuchasJ2EEor.NETshouldnotaffecttheSOAusers.Weshouldalsobeabletoreconsiderandsubstitutea“better”serviceimplementationifoneisavailable,andwithbetterqualityofservicecharacteristics.ThebusinessdriversforanewService-orienteddesignimportantservice-orientedterminology:Services:Logicalentities,thecontractsdefinedbyoneormorepublishedinterfaces.Serviceprovider:Thesoftwareentitythatimplementsaservicespecification.Serviceconsumer(orrequestor):Thesoftwareentitythatcallsaserviceprovider.Traditionally,thisistermeda“client”.Aserviceconsumercanbeanend-userapplicationoranotherservice.Servicelocator:Aspecifickindofserviceproviderthatactsasaregistryandallowsforthelookupofserviceproviderinterfacesandservicelocations.Servicebroker:Aspecifickindofserviceproviderthatcanpassonservicerequeststooneormoreadditionalserviceproviders.Service-orienteddesignimportaInterface-baseddesignInbothcomponentandservicedevelopment,thedesignoftheinterfacesisdonesuchthatasoftwareentityimplementsandexposesakeypartofitsdefinition.Therefore,thenotionandconceptof“interface”iskeytosuccessfuldesigninbothcomponent-basedandservice-orientedsystems.Thefollowingaresomekeyinterface-relateddefinitions:Interface:Definesasetofpublicmethodsignatures,logicallygroupedbutprovidingnoimplementation.Aninterfacedefinesacontractbetweentherequestorandproviderofaservice.Anyimplementationofaninterfacemustprovideallmethods.Publishedinterface:Aninterfacethatisuniquelyidentifiableandmadeavailablethrougharegistryforclientstodynamicallydiscover.Publicinterface:Aninterfacethatisavailableforclientstousebutisnotpublished,thusrequiringstaticknowledgeonthepartoftheclient.Dualinterface:Frequentlyinterfacesaredevelopedaspairssuchthatoneinterfacedependsonanother;forexample,aclientmustimplementaninterfacetocallarequestorbecausetheclientinterfaceprovidessomecallbackmechanism.Interface-baseddesignInbothInterface-baseddesignThefollowingfigureshowstheUMLdefinitionofacustomerrelationshipmanagement(CRM)service,representedasaUMLcomponent,thatimplementstheinterfacesAccountManagement,ContactManagement,andSystemsManagement.Onlythefirsttwoofthesearepublishedinterfaces,althoughthelatterisapublicinterface.NotethattheSystemsManagementinterfaceandManagementServiceinterfaceformadualinterface.Interface-baseddesignThefollLayeredapplicationarchitecturesObject-orientedtechnologyandlanguagesaregreatwaystoimplementcomponents.Whilecomponentsarethebestwaytoimplementservices,thoughonehastounderstandthatagoodcomponent-basedapplicationdoesnotnecessarilymakeangoodservice-orientedapplication.Theterm“theapplicationedge”reflectsthefactthataserviceisagreatwaytoexposeanexternalviewofasystem,withinternalreuseandcompositionusingtraditionalcomponentdesign.LayeredapplicationarchitectuAcloserlookatservice-orientedarchitectureService-orientedarchitecturepresentsanapproachforbuildingdistributedsystemsthatdeliverapplicationfunctionalityasservicestoeitherend-userapplicationsorotherservices.Itiscomprisedofelementsthatcanbecategorizedintofunctionalandqualityofservice.Acloserlookatservice-orienAcloserlookatservice-orientedarchitectureFunctionalaspectsinclude:Transportisthemechanismusedtomoveservicerequestsfromtheserviceconsumertotheserviceprovider,andserviceresponsesfromtheserviceprovidertotheserviceconsumer.ServiceCommunicationProtocolisanagreedmechanismthattheserviceproviderandtheserviceconsumerusetocommunicatewhatisbeingrequestedandwhatisbeingreturned.ServiceDescriptionisanagreedschemafordescribingwhattheserviceis,howitshouldbeinvoked,andwhatdataisrequiredtoinvoketheservicesuccessfully.Servicedescribesanactualservicethatismadeavailableforuse.BusinessProcessisacollectionofservices,invokedinaparticularsequencewithaparticularsetofrules,tomeetabusinessrequirement.Notethatabusinessprocesscouldbeconsideredaserviceinitsownright,whichleadstotheideathatbusinessprocessesmaybecomposedofservicesofdifferentgranularities.TheServiceRegistryisarepositoryofserviceanddatadescriptionswhichmaybeusedbyserviceproviderstopublishtheirservices,andserviceconsumerstodiscoverorfindavailableservices.Theserviceregistrymayprovideotherfunctionstoservicesthatrequireacentralizedrepository.Acloserlookatservice-orienAcloserlookatservice-orientedarchitectureQualityofserviceaspectsinclude:Policyisasetofconditionsorrulesunderwhichaserviceprovidermakestheserviceavailabletoconsumers.Thereareaspectsofpolicywhicharefunctional,andaspectswhichrelatetoqualityofservice;thereforewehavethepolicyfunctioninbothfunctionalandqualityofserviceareas.Securityisthesetofrulesthatmightbeappliedtotheidentification,authorization,andaccesscontrolofserviceconsumersinvokingservices.Transactionisthesetofattributesthatmightbeappliedtoagroupofservicestodeliveraconsistentresult.Forexample,ifagroupofthreeservicesaretobeusedtocompleteabusinessfunction,allmustcompleteornonemustcomplete.Managementisthesetofattributesthatmightbeappliedtomanagingtheservicesprovidedorconsumed.Acloserlookatservice-orienSOAcollaborationsThefollowingfigureshowsthecollaborationsinaservice-orientedarchitecture.Thecollaborationsfollowsthe“find,bindandinvoke”paradigm.Aserviceconsumerperformsdynamicservicelocationbyqueryingtheserviceregistryforaservicethatmatchesitscriteria.Iftheserviceexists,theregistryprovidestheconsumerwiththeinterfacecontractandtheendpointaddressfortheservice.SOAcollaborationsThefollowinSOAcollaborationsTherolesinaservice-orientedarchitectureare:Serviceconsumer:Theserviceconsumerisanapplication,asoftwaremoduleoranotherservicethatrequiresaservice.Itinitiatestheenquiryoftheserviceintheregistry,bindstotheserviceoveratransport,andexecutestheservicefunction.Theserviceconsumerexecutestheserviceaccordingtotheinterfacecontract.Serviceprovider:Theserviceproviderisanetwork-addressableentitythatacceptsandexecutesrequestsfromconsumers.Itpublishesitsservicesandinterfacecontracttotheserviceregistrysothattheserviceconsumercandiscoverandaccesstheservice.Serviceregistry:Aserviceregistryistheenablerforservicediscovery.Itcontainsarepositoryofavailableservicesandallowsforthelookupofserviceproviderinterfacestointerestedserviceconsumers.Eachentityintheservice-orientedarchitecturecanplayone(ormore)ofthethreerolesofserviceprovider,consumerandregistry.SOAcollaborationsTherolesinSOAcollaborationsTheoperationsinaservice-orientedarchitectureare:Publish:Tobeaccessible,aservicedescriptionmustbepublishedsothatitcanbediscoveredandinvokedbyaserviceconsumer.Find:Aservicerequestorlocatesaservicebyqueryingtheserviceregistryforaservicethatmeetsitscriteria.Bindandinvoke:Afterretrievingtheservicedescription,theserviceconsumerproceedstoinvoketheserviceaccordingtotheinformationintheservicedescription.Theartifactsinaservice-orientedarchitectureare:Service:Aservicethatismadeavailableforusethroughapublishedinterfacethatallowsittobeinvokedbytheserviceconsumer.Servicedescription:Aservicedescriptionspecifiesthewayaserviceconsumerwillinteractwiththeserviceprovider.Itspecifiestheformatoftherequestandresponsefromtheservice.Thisdescriptionmayspecifyasetofpreconditions,postconditionsand/orqualityofservice(QoS)levels.SOAcollaborationsTheoperatioSOAcollaborationsInadditiontodynamicservicediscoveryanddefinitionofaserviceinterfacecontract,aservice-orientedarchitecturehasthefollowingcharacteristics:Servicesareself-containedandmodular.Servicessupportinteroperability.Servicesarelooselycoupled.Servicesarelocation-transparent.Servicesarecompositemodules,comprisedofcomponents.Thesecharacteristicsarealsocentraltofulfillingtherequirementsforane-businessondemand?operationalenvironment.Finally,service-orientedarchitectureisnotanewnotion.SOAcollaborationsInadditionSponentsAserviceisacoarse-grainedprocessingunitthatconsumesandproducessetsofobjectspassed-by-value.Itisnotthesameasanobjectinprogramminglanguageterms.Instead,itisperhapsclosertotheconceptofabusinesstransactionsuchasaCICS?orIMS?transactionthantoaremoteCORBAobject.Aserviceconsistsofacollectionofcomponentsthatworkinconcerttodeliverthebusinessfunctionthattheservicerepresents.Thus,incomparison,componentsarefiner-grainedthanservices.Inaddition,whileaservicemapstoabusinessfunction,acomponenttypicallymapstobusinessentitiesandthebusinessrulesthatoperateonthem.Asanexample,letuslookatthePurchaseOrdercomponentmodelfortheWS-ISupplyChainManagementsample.SponentsAserviSponentsInacomponent-baseddesign,componentsarecreatedtocloselymatchbusinessentities(suchasCustomer,PurchaseOrder,OrderItem)andencapsulatethebehaviorthatmatchestheentities’expectedbehavior.PurchaseOrdercomponentprovidesfunctionstoobtaininformationaboutthelistofproductsorderedandthetotalamountoftheorderItemcomponentprovidesfunctionstoobtaininformationaboutthequantityandpriceoftheproductordered.Inaservice-orienteddesign,servicesarenotdesignedbasedonbusinessentities.Instead,eachserviceisaholisticunitthatmanagesoperationsacrossasetofbusinessentities.Forexample,acustomerservicewillrespondtoanyrequestfromanyothersystemorservicethatneedstoaccesscustomerinformation.Thecustomerservicecanprocessarequesttoupdatecustomerinformation;add,update,deleteinvestmentportfolios;andenquireaboutthecustomer’sorderhistory.Thecustomerserviceownsallthedatarelatedtothecustomersitismanagingandiscapableofmakingotherserviceinquiriesonbehalfofthecallingpartyinordertoprovideaunifiedcustomerserviceview.Thismeansaserviceisamanagerobjectthatcreatesandmanagesitssetcomponents.SponentsInacoService-orientedarchitecturebenefitsWithaservice-orientedarchitecture,wecanrealizeseveralbenefitstohelporganizationssucceedinthedynamicbusinesslandscapeoftoday:Leverageexistingassets.Easiertointegrateandmanagecomplexity.Moreresponsiveandfastertime-to-market.Reducecostandincreasereuse.Bereadyforwhatliesahead.Service-orientedarchitectureisbynomeansasilverbullet,andmigrationtoSOAisnotaneasytask.Ratherthanmigratingthewholeenterprisetoaservice-orientedarchitectureovernight,therecommendedapproachistomigrateanappropriatesubsetofbusinessfunctionsasthebusinessneedarisesorisanticipated.Service-orientedarchitectureSOA的疑問在我的系統(tǒng)中，所有的功能都包裝成了Web

Service，現(xiàn)在我的系統(tǒng)是否就是SOA架構(gòu)了？協(xié)議獨立、位置透明、松散耦合高度動態(tài)性SOA的疑問在我的系統(tǒng)中，所有的功能都包裝成了WebSerSOA的疑問Services與

Components的差異是什么？問題域vs.解決域集成方式我們的機遇SOA的疑問Services與Components的差異863計劃信息技術(shù)領(lǐng)域

2007年度專題課題申請指南（節(jié)選）專題一：智能感知與先進計算技術(shù)專題WhatisSoftwareArchitecture探索導(dǎo)向類課題8．服務(wù)計算技術(shù)主要研究內(nèi)容（可從以下內(nèi)容中選擇其一申請課題）：（1）服務(wù)描述與發(fā)現(xiàn)、可信的服務(wù)資源組織與管理；（2）可靠的服務(wù)組合方法與驗證；（3）動態(tài)的服務(wù)組合。說明與要求：要求完成相應(yīng)的軟件原型系統(tǒng)；獲得軟件著作權(quán)和申請專利，或以開放源碼形式發(fā)布。863計劃信息技術(shù)領(lǐng)域

2007年度專題課題申請指南（節(jié)選）ClassicSOALayersClassicSOALayers企業(yè)級應(yīng)用系統(tǒng)體系架構(gòu)SOA概述課件企業(yè)級應(yīng)用系統(tǒng)體系架構(gòu)SOA概述課件企業(yè)級應(yīng)用系統(tǒng)體系架構(gòu)SOA概述課件ModelsofSOADJBI（JavaBusinessIntegration）2005.8JSR208為JBI組件（包括服務(wù)引擎和綁定組件）的開發(fā)者建立一套標(biāo)準(zhǔn)的服務(wù)提供者接口SPI。抽象的協(xié)議無關(guān)的消息交換和規(guī)格化消息。提供一套標(biāo)準(zhǔn)的JBI組件間消息交換機制。建立一個標(biāo)準(zhǔn)來封裝JBI組件，并為這些組件部署服務(wù)。定義一些管理監(jiān)控掛鉤（hooks），用于以后開發(fā)針對各種特定問題域的標(biāo)準(zhǔn)工具。提供服務(wù)引擎和綁定組件實現(xiàn)的復(fù)雜性和多樣性。允許不同的供應(yīng)商發(fā)布JBI組件，這些組件之間能夠可靠地互操作，由這些組件（在JBI基礎(chǔ)設(shè)施之上）構(gòu)建的系統(tǒng)可以集中管理。28ModelsofSOADJBI（JavaBusinesModelsofSOADJBI（JavaBusinessIntegration）29ModelsofSOADJBI（JavaBusinesModelsofSOADSCA(ServiceComponentArchitecture)/SDO(ServiceDataObject)SCA定義了如何創(chuàng)建服務(wù)組件以及如何將服務(wù)組件組裝成業(yè)務(wù)解決方案的通用方法。SCA由一系列規(guī)范組成,包括說明如何用某種具體語言（如Java、C++、Spring、BPEL等）實現(xiàn)業(yè)務(wù)服務(wù)組件的組件實現(xiàn)(ComponentImplementation)規(guī)范；如何定義組合服務(wù)組件結(jié)構(gòu)的裝配(Assembly)模型；如何使用各種訪問方法（如Webservices、JMS、RMI-IIOP、REST等）的綁定(Binding)規(guī)范；如何將基礎(chǔ)設(shè)施服務(wù)（如安全、事務(wù)、可靠消息等）加到解決方案的策略框架(PolicyFramework)SDO(ServiceDataObject)提供了一種通用的數(shù)據(jù)編程架構(gòu)和API，SCA組件可以通過傳遞服務(wù)數(shù)據(jù)對象來交換數(shù)據(jù)。SDO體系結(jié)構(gòu)中的基本概念主要有數(shù)據(jù)對象（DataObject）、數(shù)據(jù)圖（datagraph）和數(shù)據(jù)訪問服務(wù)DAS(DataAccessServices)。30ModelsofSOADSCA(ServiceCompModelsofSOADSCA(ServiceComponentArchitecture)/SDO(ServiceDataObject)31ModelsofSOADSCA(ServiceCompModelsofSOADWindowsServer2003+.NETFramework3.0+BizTalkServer2006R2BizTalkServerMessageroutingMessagevalidationMessagetransformation)CentralizedexceptionmanagementExtensibleadapterframeworkServiceorchestrationBusinessrulesengineBusinessactivitymonitoring32ModelsofSOADWindowsServer2ModelsofSOADWindowsServer2003+.NETFramework3.0+BizTalkServer2006R233ModelsofSOADWindowsServer2TypicalSOAAPPLICATIONS34TypicalSOAAPPLICATIONS34EndTobecontinued35EndTobecontinued35企業(yè)級應(yīng)用系統(tǒng)體系架構(gòu)（八）

SOA概述ChenHaopengTuesday,November22,2022References：IBMRedbook:PatternsServiceOrientedArchitectureandWebServices36企業(yè)級應(yīng)用系統(tǒng)體系架構(gòu)（八）

SOAThebusinessdriversforanewapproachWhileITexecutiveshavebeenfacingthechallengeofcuttingcostsmaximizingtheutilizationofexistingtechnologyAtthesametimetheyhavetocontinuouslystrivetoservecustomersbetterbemorecompetitivebemoreresponsivetothebusiness’sstrategicpriorities.Therearetwounderlyingthemesbehindallofthesepressures:HeterogeneityandchangeThebusinessdriversforanewThebusinessdriversforanewapproachHeterogeneity

Mostenterprisestodaycontainarangeofdifferentsystems,applications,andarchitecturesofdifferentagesandtechnologies.Integratingproductsfrommultiplevendorsandacrossdifferentplatformswerealmostalwaysanightmare.Butwealsocannotaffordtotakeasingle-vendorapproachtoIT,becauseapplicationsuitesandthesupportinginfrastructurearesoinflexible.ChangeGlobalizationande-businessareacceleratingthepaceofchange.Improvementsintechnologycontinuetoaccelerate,feedingtheincreasedpaceofchangingcustomerrequirements.ThebusinessdriversforanewThebusinessdriversforanewapproachAsaresult,businessorganizationsareevolvingfromthevertical,isolatedbusinessdivisionsofthe1980’sandearliertothehorizontalbusiness-process-focusedstructuresofthe1980’sand1990’stowardsthenewecosystembusinessparadigm.Businessservicesnowneedtobecomponentizedanddistributed.Thereisafocusontheextendedsupplychain,enablingcustomerandpartneraccesstobusinessservices.ThebusinessdriversforanewThebusinessdriversforanewapproachQuestions:HowdoImakemyITenvironmentmoreflexibleandresponsivetotheeverchangingbusinessrequirements?Howcanwemakethoseheterogeneoussystemsandapplicationscommunicateasseamlesslyaspossible?Howcanweachievethebusinessobjectivewithoutbankruptingtheenterprise?CurrentlymanyITexecutivesandprofessionalsalikebelievethatnowwearegettingreallyclosetoprovidingasatisfactoryanswerwithservice-orientedarchitecture.ThebusinessdriversforanewThebusinessdriversforanewapproachInordertoalleviatetheproblemsofheterogeneity,interoperabilityandeverchangingrequirements,suchanarchitectureshouldprovideaplatformforbuildingapplicationserviceswiththefollowingcharacteristics:LooselycoupledLocationtransparentProtocolindependentBasedonsuchaservice-orientedarchitecture,aserviceconsumerdoesnotevenhavetocareaboutaparticularserviceitiscommunicatingwithbecausetheunderlyinginfrastructure,orservice“bus”,willmakeanappropriatechoiceonbehalfoftheconsumer.Theinfrastructurehidesasmanytechnicalitiesaspossiblefromarequestor.ParticularlytechnicalspecificitiesfromdifferentimplementationtechnologiessuchasJ2EEor.NETshouldnotaffecttheSOAusers.Weshouldalsobeabletoreconsiderandsubstitutea“better”serviceimplementationifoneisavailable,andwithbetterqualityofservicecharacteristics.ThebusinessdriversforanewService-orienteddesignimportantservice-orientedterminology:Services:Logicalentities,thecontractsdefinedbyoneormorepublishedinterfaces.Serviceprovider:Thesoftwareentitythatimplementsaservicespecification.Serviceconsumer(orrequestor):Thesoftwareentitythatcallsaserviceprovider.Traditionally,thisistermeda“client”.Aserviceconsumercanbeanend-userapplicationoranotherservice.Servicelocator:Aspecifickindofserviceproviderthatactsasaregistryandallowsforthelookupofserviceproviderinterfacesandservicelocations.Servicebroker:Aspecifickindofserviceproviderthatcanpassonservicerequeststooneormoreadditionalserviceproviders.Service-orienteddesignimportaInterface-baseddesignInbothcomponentandservicedevelopment,thedesignoftheinterfacesisdonesuchthatasoftwareentityimplementsandexposesakeypartofitsdefinition.Therefore,thenotionandconceptof“interface”iskeytosuccessfuldesigninbothcomponent-basedandservice-orientedsystems.Thefollowingaresomekeyinterface-relateddefinitions:Interface:Definesasetofpublicmethodsignatures,logicallygroupedbutprovidingnoimplementation.Aninterfacedefinesacontractbetweentherequestorandproviderofaservice.Anyimplementationofaninterfacemustprovideallmethods.Publishedinterface:Aninterfacethatisuniquelyidentifiableandmadeavailablethrougharegistryforclientstodynamicallydiscover.Publicinterface:Aninterfacethatisavailableforclientstousebutisnotpublished,thusrequiringstaticknowledgeonthepartoftheclient.Dualinterface:Frequentlyinterfacesaredevelopedaspairssuchthatoneinterfacedependsonanother;forexample,aclientmustimplementaninterfacetocallarequestorbecausetheclientinterfaceprovidessomecallbackmechanism.Interface-baseddesignInbothInterface-baseddesignThefollowingfigureshowstheUMLdefinitionofacustomerrelationshipmanagement(CRM)service,representedasaUMLcomponent,thatimplementstheinterfacesAccountManagement,ContactManagement,andSystemsManagement.Onlythefirsttwoofthesearepublishedinterfaces,althoughthelatterisapublicinterface.NotethattheSystemsManagementinterfaceandManagementServiceinterfaceformadualinterface.Interface-baseddesignThefollLayeredapplicationarchitecturesObject-orientedtechnologyandlanguagesaregreatwaystoimplementcomponents.Whilecomponentsarethebestwaytoimplementservices,thoughonehastounderstandthatagoodcomponent-basedapplicationdoesnotnecessarilymakeangoodservice-orientedapplication.Theterm“theapplicationedge”reflectsthefactthataserviceisagreatwaytoexposeanexternalviewofasystem,withinternalreuseandcompositionusingtraditionalcomponentdesign.LayeredapplicationarchitectuAcloserlookatservice-orientedarchitectureService-orientedarchitecturepresentsanapproachforbuildingdistributedsystemsthatdeliverapplicationfunctionalityasservicestoeitherend-userapplicationsorotherservices.Itiscomprisedofelementsthatcanbecategorizedintofunctionalandqualityofservice.Acloserlookatservice-orienAcloserlookatservice-orientedarchitectureFunctionalaspectsinclude:Transportisthemechanismusedtomoveservicerequestsfromtheserviceconsumertotheserviceprovider,andserviceresponsesfromtheserviceprovidertotheserviceconsumer.ServiceCommunicationProtocolisanagreedmechanismthattheserviceproviderandtheserviceconsumerusetocommunicatewhatisbeingrequestedandwhatisbeingreturned.ServiceDescriptionisanagreedschemafordescribingwhattheserviceis,howitshouldbeinvoked,andwhatdataisrequiredtoinvoketheservicesuccessfully.Servicedescribesanactualservicethatismadeavailableforuse.BusinessProcessisacollectionofservices,invokedinaparticularsequencewithaparticularsetofrules,tomeetabusinessrequirement.Notethatabusinessprocesscouldbeconsideredaserviceinitsownright,whichleadstotheideathatbusinessprocessesmaybecomposedofservicesofdifferentgranularities.TheServiceRegistryisarepositoryofserviceanddatadescriptionswhichmaybeusedbyserviceproviderstopublishtheirservices,andserviceconsumerstodiscoverorfindavailableservices.Theserviceregistrymayprovideotherfunctionstoservicesthatrequireacentralizedrepository.Acloserlookatservice-orienAcloserlookatservice-orientedarchitectureQualityofserviceaspectsinclude:Policyisasetofconditionsorrulesunderwhichaserviceprovidermakestheserviceavailabletoconsumers.Thereareaspectsofpolicywhicharefunctional,andaspectswhichrelatetoqualityofservice;thereforewehavethepolicyfunctioninbothfunctionalandqualityofserviceareas.Securityisthesetofrulesthatmightbeappliedtotheidentification,authorization,andaccesscontrolofserviceconsumersinvokingservices.Transactionisthesetofattributesthatmightbeappliedtoagroupofservicestodeliveraconsistentresult.Forexample,ifagroupofthreeservicesaretobeusedtocompleteabusinessfunction,allmustcompleteornonemustcomplete.Managementisthesetofattributesthatmightbeappliedtomanagingtheservicesprovidedorconsumed.Acloserlookatservice-orienSOAcollaborationsThefollowingfigureshowsthecollaborationsinaservice-orientedarchitecture.Thecollaborationsfollowsthe“find,bindandinvoke”paradigm.Aserviceconsumerperformsdynamicservicelocationbyqueryingtheserviceregistryforaservicethatmatchesitscriteria.Iftheserviceexists,theregistryprovidestheconsumerwiththeinterfacecontractandtheendpointaddressfortheservice.SOAcollaborationsThefollowinSOAcollaborationsTherolesinaservice-orientedarchitectureare:Serviceconsumer:Theserviceconsumerisanapplication,asoftwaremoduleoranotherservicethatrequiresaservice.Itinitiatestheenquiryoftheserviceintheregistry,bindstotheserviceoveratransport,andexecutestheservicefunction.Theserviceconsumerexecutestheserviceaccordingtotheinterfacecontract.Serviceprovider:Theserviceproviderisanetwork-addressableentitythatacceptsandexecutesrequestsfromconsumers.Itpublishesitsservicesandinterfacecontracttotheserviceregistrysothattheserviceconsumercandiscoverandaccesstheservice.Serviceregistry:Aserviceregistryistheenablerforservicediscovery.Itcontainsarepositoryofavailab